Plant elicitors enhance plant defense against pathogen attacks by inducing systemic acquired resistance (SAR) with no or low direct fungicidal activity. Here we report the synthesis of a novel plant elicitor candidate LY5-24-2 [3,4-dichloro-N-(3-chloro-5-(trifluoromethyl)pyridin-2-yl)isothiazole-5-carboxamide] and evaluation of its SAR inducing activity. Bioassays indicated that LY5-24-2 did not show significant anti-fungal activity but provided long-lasting resistance in Arabidopsis thaliana (A. thaliana) through promoting the accumulation of lignin, cellulose and pectin by 60.1%, 82.4% and 305.6%, respectively, at a concentration of 100 µM. LY5-24-2 also facilitated the closure of leaf stomata and increased the intracellular free Ca²⁺ by 47.8%, induced reactive oxygen species (ROS) accumulation, and inhibited the activity of ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6) by 38.9% and 34.0%, respectively, as compared with the control at a concentration of 100 µM. LY5-24-2 induced SAR in plants and was dependent on the NPR1-mediated SA pathway by up-regulating expression of 2273 genes in A. thaliana. Meanwhile, LY5-24-2 also improved cucumber (Cucumis sativus L.) defense against Pseudoperonospora cubensis (P. cubensis) through promoting ROS accumulation and inhibiting activity of APX and CAT by 30.7% and 23.1%, respectively. Its expression of SA signaling genes CsNPR1, CsPR4 and CsPR5 was enhanced by 10.8, 5.8 and 6.6 times, respectively. These results demonstrated that LY5-24-2 is a novel elicitor candidate for plant protection via inducing SAR.

During China’s 41st Antarctic research expedition, samples were collected from wildlife on the Fildes Peninsula, South Shetland Islands, Antarctica. Real-time RT-PCR screening confirmed H5N1 positivity, representing the first identification of the virus in brown skuas on the Fildes Peninsula. Whole-genome sequences obtained from positive samples via next-generation sequencing were subjected to phylogenetic and phylogeographic analyses. The results revealed that these Antarctic strains are most closely related to H5N1 viruses circulating in South America, particularly from Peru and Chile, suggesting a likely introduction via avian migration routes. Furthermore, a unique 17-amino-acid deletion was identified in the stalk region of the neuraminidase (NA) gene, which is uncommon among globally sampled clade 2.3.4.4b variants. This study confirms the arrival of HPAI H5N1 in the Antarctic continent and underscores the necessity for enhanced surveillance to understand the viral ecology and potential risks within this unique ecosystem.

Plants rely on the innate immune system to sense and respond to a wide range of lifestyle pathogens and to facilitate their survival in natural ecosystems. Pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) are designated as a two-branched system of innate immunity. Although PTI/ETI share a series of downstream molecular events, systematic analysis of convergent and divergent signaling in PTI/ETI is currently lacking. The phytohormones salicylic acid (SA) and jasmonic acid (JA) are considered to constitute the hormonal backbone of plant immunity, are functionally antagonistic, and play essential roles in defending against biotrophic and necrotrophic pathogens, respectively. However, the distinct performance of two phytohormones in PTI/ETI remains unclear. Here, we systemically investigate and validate the reprogramming of molecular networks during PTI and ETI. Using publicly available Arabidopsis RNA sequence data from 560 samples, we construct a co-expression network under Mock conditions and then explore the differential expression/co-expression changes during PTI, ETI, and Pto DC3000 infection. During PTI and ETI, one-third of genes in the Arabidopsis genome exhibit the same directional differential expression in a manner independent of JA/ethylene/PAD4/SA signaling but show differential co-expression patterns. However, the defense phytohormone network is required for defense against Pto DC3000 infection. We also exhibit the use of this network in prioritizing genes that functioned closely with the proteins directly targeted by elicitors. Overall, this study will deepen our understanding of plant transcriptome in plant immunity and provide new insights into the mode of action of elicitors.

Mosquitoes harbor diverse microbial communities that influence their potential to transmit pathogens. However, the ecological drivers shaping these microbiomes, particularly in under-sampled regions like Africa, remain poorly resolved. We conducted a large-scale metatranscriptomic survey of 3,940 Aedes and Culex mosquitoes from diverse ecological zones across Kenya. Our analyses revealed that viruses dominated the overall transcriptome, while bacteria exhibited the greatest taxonomic richness. Geographic location emerged as the primary driver of microbial community structure, whereas host genus identity shaped virome diversity at local or city-level scales. Culex mosquitoes harbored higher viral richness, particularly in coastal regions, while Aedes supported more diverse bacterial assemblages. Microbial co-occurrence networks exhibited distinct topologies across hosts: Culex networks featured cross-domain interactions and viral keystone taxa, whereas Aedes networks were more cohesive and robust, centered on bacterial hubs. We identified 102 distinct viruses from 24 families, including 31 putative novel RNA viruses. Segment-resolved phylogenies revealed cryptic clades within Bunyavirales, Picornavirales, and other lineages. Collectively, our findings highlight the scale-dependent influences of geography and host identity on mosquito microbiomes in East Africa and demonstrate the utility of metatranscriptomics in uncovering hidden microbial diversity and ecological interactions. These insights provide a foundation for ecologically informed arthropod vector surveillance and microbiome-based intervention strategies. IMPORTANCE: Mosquitoes are more than just flying syringes; they are complex ecosystems hosting a variety of microbes. Understanding what shapes this microbial world inside mosquitoes is key to developing new control strategies. Our study of nearly 4,000 mosquitoes from Kenya reveals that where a mosquito lives matters most for its overall microbial makeup, but its genus dictates which viruses it carries. We discovered that different mosquito types have distinct microbial social networks: one type has a fragile network centered on viruses, while the other has a resilient network built around bacteria. This means that strategies to disrupt disease transmission by targeting mosquito microbes may need to be tailored to a specific mosquito genus. Our work provides a map of these microbial ecosystems, highlighting potential new viruses and offering insights for future public health surveillance and interventions.